Comorbidities and ventricular dysfunction drive excess mid-term morbidity in an Indigenous Australian coronary revascularisation cohort

Background: There is a paucity of data in regards to longer term morbidity outcomes in Indigenous Australian patients undergoing coronary artery bypass grafting (CABG). No comparative data on re-infarction, stroke or reintervention rates exist. Outcome data following percutaneous coronary intervention (PCI)is also extremely limited. Addressing this gap in knowledge forms the major aim of our study. Methods: This was a single centre cohort study conducted at the Townsville Hospital, Australia which provides tertiary adult cardiac surgical services to the northern parts of the state of Queensland. It incorporated consecutive patients (n = 350)undergoing isolated CABG procedures, 2008–2010, 20.9% (73/350)of whom were Indigenous Australians. The main outcome measures were major adverse cardiac or cerebrovascular events (MACCE)at mid-term follow-up (mean 38.9 months). Results: The incidence of MACCE among Indigenous Australian patients was approximately twice that of non-Indigenous patients at mid-term follow-up (36.7% vs. 18.6%; p = 0.005; OR 2.525 (1.291–4.880)). Following adjustment for preoperative and operative variables, Indigenous Australian status itself was not significantly associated with MACCE (AOR 1.578 (0.637–3.910)). Significant associations with MACCE included renal impairment (AOR 2.198 (1.010–4.783))and moderate-severe left ventricular impairment (AOR 3.697 (1.820–7.508)). An association between diabetes and MACCE failed to reach statistical significance (AOR 1.812 (0.941–3.490)). Conclusions: Indigenous Australians undergoing CABG suffer an excess of MACCE when followed-up in the longer term. High rates of comorbidities in the Indigenous Australian population likely play an aetiological role.